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A man fires a bullet of mass 200 g at a speed of 5 m/s. The gun is of one kg mass. By what velocity does the gun rebound backwards?

Asked in AIPMT 1996 · Recoil and explosions

Answer: (1) 1 m/s

Step-by-step solution

Given: bullet m=200 g =0.2 kg at 5 m/s; gun M=1 kg.

Idea: the pair starts at rest, so the two momenta afterwards must cancel.

Bullet momentum: mv=0.2×5=1 kg m s⁻¹.

Gun momentum must be equal and opposite: MV=1.

V=1/1.

V=1 m/s, backwards.

Why the other options are wrong

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